Superabsorbent polymers (SAP) have been widely applied in the sanitation, medical, and agriculture industries, and also other various industries. For example, superabsorbent polymers have been used in diapers, sanitary pads, or the like.
Concerns about using superabsorbent polymers are that the absorbent ability decreases severely in saline solution. In general, water absorption rate of a superabsorbent polymer in distilled water (for example, about 250 g/g) is much higher than the water absorption rate of the superabsorbent polymer in normal saline (for example, about 61 g/g.) Moreover, the water absorption rate of the superabsorbent polymer in normal saline may drop drastically under pressure (for example, 35 g/g.) In other words, the water absorption rate of the superabsorbent polymer in a saline environment may be one-seventh of that in the distilled water, such that seven times that the amount of the superabsorbent polymer is required to achieve the same absorption rate. Therefore, sanitary products such as diapers and sanitary pads are thick, and heavy.